This invention relates to a platen roll of impact type printer according to which noises caused at printing and the weight thereof can be reduced.
Conventional platen rolls used in printers of impact printing type are one, as shown in FIG. 1 (a), which comprises a metallic shaft 1 and a highly hard rubber layer 2 provided concentrically around the metallic shaft and one, as shown in FIG. 1 (b), which comprises a roll comprising integrally combined metallic shaft 1 and metallic cylinder 3 and highly hard rubber layer 2 provided outside said roll. Such platen rolls as above have been widely used. However, these platen rolls have the following problems:
(1) Loud noise occurs at printing and such noise is undesirable for health of operators and for indoor working environment.
(2) Weight of conventional platens is heavy and accordingly driving motor should be larger. There are not desired for compacting of devices and power saving.
Various attempts have been made to improve or modify the rolls which are considered to be main cause for occurrence of noises. There are proposals such as reduction of noises by reconstruction of shaft structure, namely, reduction of noises by increase of weight and reduction of noises by employing tube-like shaft and forming therein a foam layer of urethane as a vibration damping layer. However, these proposals have not been satisfactory. With reference to rubber, there have also been some proposals to reduce noises by employing a cover rubber of low hardness or by employing a two-layer surface cover rubber of a low hardness inner layer and a high hardness surface layer. These are also not preferred because of low printing ability.